Turning Global Challenge into Performance Advantage The Power of Hot Baths for Marathon Runners

The Global Challenge of Heat

With global temperatures on the rise, the challenge of running in hot conditions has become a universal concern. Yet, within this challenge lies a remarkable opportunity - a chance to transform a global obstacle into a performance advantage. Enter the world of hot baths: a potent tool for enhancing athletic performance, especially for marathon runners. 

Pragmatic Approach to Heat Training/Acclimation

For marathon runners like Phil Sesemann and Emile Cairess, a large volume of moderate-intensity exercise must be carefully managed to achieve the desired adaptation without excessive fatigue and maladaptation (Mujika et al., 2018). Prior to competing in hot environments heat acclimation forms a central focus, requiring careful integration. By acclimatizing early and undertaking subsequent regular maintenance thermal exposures such as thermal layered runs and hot water immersion, this ensures increased heat strain without replacing planned training or imposing additional external training load.  

The Mechanics of Hot Baths

Hot baths involve immersing the body in hot water (submerged to the neck), typically set between 39.5 to 40 degrees Celsius, immediately after a workout and for up to 40-minutes. This practice is not just about soothing sore muscles, but also serves as a rigorous training modality that primes the body for high-heat environments. The concept is simple: by combining a rise in core body temperature with elevated skin temperature, hot baths provide a dual stimulus that can trigger significant physiological adaptations.

This dual stimulus is the foundation of heat acclimation, which involves the body's gradual adjustment to increased temperatures. The benefits include a lower resting core body temperature, an increased sweat rate, expanded blood volume, and improved thermal perception - all critical for endurance athletes. Recent evidence by McIntyre et al., (2022) suggests that hot water immersion can amplify these adaptations more effectively than traditional exercise heat acclimation methods.

Practicality and Accessibility

One of the most compelling aspects of hot baths is their practicality. Unlike certain heat acclimation strategies that require specialist facilities or equipment, hot water immersion can be done at home. This makes it a more accessible option for a broader range of athletes, from elite marathoners to recreational runners. While it's advisable to have supervision, particularly when first incorporating hot baths into a training routine, the setup is straightforward and can be tailored to individual needs. Commercially available tympanic thermometers can be purchased and offer a suitable substitute for expensive ingestible telemetric pills or invasive rectal probes for monitoring core body temperature during hot water immersion. 

Benefits Beyond Heat Acclimation

The advantages of hot baths extend beyond heat acclimation. Regular heat exposure accumulated over multiple weeks has been shown to increase hemoglobin mass (responsible for carrying oxygen to the muscle) and submaximal performance in elite endurance athletes (Ronnestad et al., 2022). In addition, post-exercise heating has no impact on perception of effort during subsequent exercise (Menzies et al., 2024); which is important to not compromise training quality or next day performance. 

Long-term Potential and Future Implications

The long-term potential of hot baths in athletic training cannot be overstated. As the global climate continues to change, the ability to perform in hot conditions will only become more critical. By incorporating hot baths into their training, athletes are not just preparing for the next race but are also future-proofing their performance. This approach turns a global challenge into a competitive advantage, positioning athletes to excel in increasingly common high-heat scenarios.

Hot baths offer a unique and effective way to enhance performance, particularly for marathon runners. The dual stimulus of elevated core and skin temperatures promotes crucial heat adaptation responses and aids in recovery and performance enhancement. For athletes like Phil and Emile, and indeed for all runners, hot water immersion is proving to be the best ‘bang for your buck’ in the quest for excellence.